(x power of 6-12x power of 3+35)divide)x power of 3- 7)

i dunno what to do

Try to factorize the numerator, treating x³ as a single unit, so x6 would be (x³)².

You will find common factors between the numerator and denominator.

(x6-12x3+35)/(x3-7)
=(x³-7)(x³-5)/(x³-7)
=x³-5